The Rover Concept for the ESA ExoMars Mission

1. The Rover Concept for the ESA ExoMars Mission G. Gianfiglio, M. van Winnendael, J. Vago, P. Baglioni (European Space Agency) F. Ravera (Alcatel Alenia Space Italia) L. Waugh - EADS AstriumLtd (UK) IEEE-ICRA 2007 workshop on Space Robotics Rome, 14 April 2007 Space Robotics Workshop ICRA07

2. Automation and Robotics Section (TEC-MMA) The Rover Concept for the ESA ExoMars Mission Complementary Remarks By L. Joudrier ESA-Robotics Section Space Robotics Workshop ICRA07

3. Forewords • Presentation of Rover – see proceedings for the mission details • All material presented is subject to change due to the on-going and coming industrial studies. • Additional pieces of information aiming to be potential seeds for discussions during this workshop. Space Robotics Workshop ICRA07

4. Presentation Outline • Forewords • ExoMars Mission • Objectives • Status • Overview • ExoMars Rover • Current baseline • Vehicle overview • Payload Support Equipment • Pasteur Payload • Surface Operations • RHUs & Planetary Protection • Considerations about the ExoMars Rover • Locomotion subsystem • Navigation • Autonomy • Planetary Protection Space Robotics Workshop ICRA07

5. Presentation Outline • Forewords • ExoMars Mission • Objectives • Status • Overview • ExoMars Rover • Current baseline • Vehicle overview • Payload Support Equipment • Pasteur Payload • Surface Operations • RHUs & Planetary Protection • Considerations about the ExoMars Rover • Locomotion subsystem • Navigation • Autonomy • Planetary Protection Space Robotics Workshop ICRA07

6. Mission Objectives • ExoMars is the first ESA led robotic mission of the Aurora Exploration Programme, combining demonstration of key enabling exploration technologies with major scientific investigations • Main technology demonstration objectives: • Safe Entry, Descent and Landing of a large size payload (Descent Module) • Surface mobility (Rover) and access to the subsurface (Drill) • Main scientific objectives: • Search for traces of past and present life and characterize Martian chemistry and water distribution • Improve the knowledge on Martian environment and identify surface hazards to future human missions Space Robotics Workshop ICRA07

7. Mission Status • Phase B1 on-going • Started in October 2005 with AAS-I as Prime Contractor • Extended to consider several options. • Selection of Major sub-contractors is completed. • ASTRIUM UK responsible for the rover • Selection of sub-contractors completed soon • SRR just completed • Implementation Review is next (May 2007) • Phase B1 to be completed by end of 2007 • Integrated Locomotion-Navigation Rover Prototype • Launch date: 2011 unlikely so target is 2013 with back up 2015/2016 launch opportunity. Space Robotics Workshop ICRA07

8. Mission Overview • Launch a Descent Module to Mars with supporting spacecraft infrastructure for LEOP and Cruise Phase • Baseline: (Carrier + DM + Rover) Soyuz from Kourou + MRO • Option 1: additional Soyuz for a relay orbiter (MRO back-up) • Option 2: Ariane5 for ExoMars + carrier upgraded as orbiter (MRO back-up) • Release Descent Module into Mars atmosphere for automatic Entry, Descent and Landing (EDL) on Mars surface • Latitudes between –15º and +45º, all longitudes / Altitude ≤ 0 m relative to the MOLA zero level • Option: vented / non-vented airbag landing system • Egress of the Rover from the landed module • Accomplish Rover surface operations • 180 sols minimum, 10 experiment cycles, ~1km distance between experiment locations Space Robotics Workshop ICRA07

9. Presentation Outline • Forewords • ExoMars Mission • Objectives • Status • Overview • ExoMars Rover • Current baseline • Vehicle overview • Payload Support Equipment • Pasteur Payload • Surface Operations • RHUs & Planetary Protection • Considerations about the ExoMars Rover • Locomotion subsystem • Navigation • Autonomy • Planetary Protection Space Robotics Workshop ICRA07

10. Rover Current Baseline • Mass ~ 180 kg (including Drill, SPDS and ~8kg Pasteur Payload) • Average Power ~ 120 W (by Solar Array assuming RHUs availability) • X-band communication link for DTE and UHF band for Proxi-link with MRO • Two Thermal Control solutions still under trade-off: with and without RHU’s Concept with RHUs Concept without RHUs Space Robotics Workshop ICRA07

11. Rover Vehicle • Navigation • Cameras (Nav. Cam, Haz. Cams) • Navigation sensors • Navigation Software (CNES) • Structure • Integrated units • Deployable mast for Cameras, IR Spectrometer and sensors • SA support and mechanisms • Locomotion • 6 wheels chassis • TTC • X-band for DTE • 2 redundant transponders • 2 redundant SSPA • 1 RFDN • 1 Small HGA (30cm dish, 24dBi gain) • UHF band for data relay with MRO • Internal redundant Proximity-1 compliant transponder • 1 LGA (quad helix) • 1 RFDN • Power • Solar Arrays • Battery (Rechargeable, Li-Ion) • PCDU • Thermal Control System (TCS) • Two options under trade-off (with and without RHUs) • Loop Heat pipes, Radiators, Passive Thermal Switches Space Robotics Workshop ICRA07

12. Payload Support Equipment • Sample Acquisition System – To obtain surface and subsurface samples for analysis; includes a subsurface drill with rod exchange and positioning mechanism & a sample delivery mechanism, plus a surface rock corer (TBC) • SPDS – To prepare and present samples to all analytical lab instruments; includes distribution mechanisms and a milling station Subsurface drill includes a miniaturised IR spectrometer for borehole investigations (Ma_Miss DIBS) Space Robotics Workshop ICRA07

13. To be accommodated into GEP Rover Scientific Payload: Pasteur CONTEXT - PanCam - IR Spectrometer - Ground Penetrating Radar - Close-up Imager - Mössbauer - Raman-LIBS external optical heads - Microscope IR - Raman - LIBS Spectrometers - XRD • The instruments development is under the responsibility of relevant National Agencies • The current total mass of the Pasteur Payload Instruments exceeds the 8 kg allocation: if necessary instruments de-scoping will be implemented in line with the available resources (Payload Confirmation Review) INSTRUMENTS SUPPORT EQUIPMENT Drill System (Surface and 2 m depth) Includes Borehole IRS Sample Preparation & Distribution System (SPDS) ORGANICS/LIFE - MOD/MOI - GC-MS - Life Marker Chip ENVIRONMENT - Dust & H2O Vapour Suite - Ionising Radiation - UV Spectrometer - Meteo Package Space Robotics Workshop ICRA07

14. Rover Surface Operations The Surface Mission is composed of a sequence of Experiment Cycles (up to 10) An Experiment Cycle consists of: Identifying the location at which to perform the Measurement Cycle (from Ground Control) Traveling to the new location (distance about 1 km between locations) Performing a full Measurement Cycle using all instruments Transmitting scientific, housekeeping and navigation data to the Relay Orbiter/Earth (Data volume ~ 1Gbit per Experiment Cycle) During night the Rover goes into a sleep mode and resumes operations the following day Space Robotics Workshop ICRA07

15. Planetary Protection & Radio-isotope Heating Units • RHUs: Accommodation/location inside the internal enclosure is subject to trade-off between easy late access, proper heat distribution and interfaces with the Rover TCS • Planetary Protection: ExoMars is a class IVc mission allowing to search for past life and organic molecules in “special regions”. This is a major driver of the mission design, AIV, especially considering possible need of late access due to RHUs. The sterilization concept is under study. The PP mission class may be revised into IVb class (TBC). Space Robotics Workshop ICRA07

16. Presentation Outline • Forewords • ExoMars Mission • Objectives • Status • Overview • ExoMars Rover • Current baseline • Vehicle overview • Payload Support Equipment • Pasteur Payload • Surface Operations • RHUs & Planetary Protection • Considerations about the ExoMars Rover • Locomotion subsystem • Navigation • Autonomy • Planetary Protection Space Robotics Workshop ICRA07

17. Locomotion Subsystem 1/2 ExoMars current baseline is the RCL-type E with formula 6*6*4+4W  Simple and light weight design passive articulated suspension  No internal averaging mechanism  Wheel-walking/peristaltic mode possible allowing highest mobility (Reuse of the motors necessary for deployment) BUT  Static stability issue depending of CoG (40 deg requirement)  Eventually less performing compared to other concepts (Type D, Crab, R-bogie) Possible improvements: Formula 6*6*6+4W or 6*6*6+6W RCL Type-E RCL Type-D Space Robotics Workshop ICRA07

18. Locomotion Subsystem 2/2 ExoMars mobility requirements: • 25 cm step obstacle • 25 deg slope on specific soil • 40deg stability any direction Improvement of traction & obstacle crossing capabilities: • Use of terramechanics to define optimum wheel design (Single Wheel Testbed built within R&D activity “Rover Chassis Evaluation Tools”) • Possible use of flexible wheels [Richter ASTRA06] • Improved design of articulated suspension via simulation tools and prototyping. • Optimising the mass and power requirements remains a challenge at the expense of the scientific payload and desirable higher locomotion capabilities. • Locomotion risks due to unknown rough terrain are mitigated by high locomotion capabilities and (conservative) navigation. Space Robotics Workshop ICRA07

19. Navigation Baseline is the use of the CNES Autonomous Navigation Software. Accurate localisation is key. Visual Odometry & target tracking are required. Solutions to definition target coordinates on ground by PIs to be experimented. Space Robotics Workshop ICRA07

20. Autonomy ExoMars will require high degree of autonomy : Ground Control Staffing, amount of Telemetry to download, large distance traverses. At least level E3 on the ECSS E70 autonomy scale (event driven reactive systems with some re-planning). ESA Relevant R&D Activities (non exhaustive): • ESA Functional Reference Model (FRM) based on a 3-layered controller architecture (Mission-Task-Actions) equivalent to deliberative-executive-functional layers. • MUROCO: Formal specification and verification Tool [Kapellos-ASTRA06]. Use ESTEREL formal language to specify/Verify the rover behaviour (state machine composing the actions and tasks). • MMOPS: On-board planning/re-planning and scheduling tool [Woods-ASTRA06] • On-board model checking (just started) will allow advanced FDIR. • 3DROV (on-going): full planetary rover simulator Space Robotics Workshop ICRA07

21. Planetary Protection Based on the facts that: • During AIV process, 80 % of the bio-burden is brought by the AIV operators. • Sterilisation “kills the spores but does not remove the bodies” that may trigger organic molecule sensitive sensors designed to detect traces of past life. ESA has initiated a feasibility study on Robotized AIV that would allow to reduce to the minimum the number of operators in the AIV clean rooms. Robotized AIV is very challenging activity where space robotics and Earth state of the art robotics would be joined. Space Robotics Workshop ICRA07

22. Conclusion ExoMars mission and rover current baselines have been briefly presented. They will evolve along with the industry work. Some relevant ESA R&D activities about rover have been presented to provide inputs to the discussion Questions ? Space Robotics Workshop ICRA07